In general, a generator includes a rotor and a stator wherein the rotor has a plurality of magnets arranged on a rotor disc in such a fashion as to be fixedly mounted to a rotary shaft, and the stator is mounted spaced apart from the rotor, coils from which voltage is induced by a line of magnetic force generated by the rotation of the rotor are arranged on a stator disc, the stator being fixedly mounted to a lateral housing. Such a basic structure of the generator is intended to output the power induced to coils of the stator through an external rotary power transmitted to the rotary shaft.
However, the rotary shaft rotates by an external rotational force to cause the rotor to rotate, and a magnetic field induced by magnets mounted on the rotor is inducted to coils of the stator to thereby produce the power from the coils. At this time, the coils of the stator induce the power and generate heat by the induced magnetic field.